Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
  • B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/02—Linings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/50—Pouring-nozzles
  • B22D41/52—Manufacturing or repairing thereof
  • B22D41/54—Manufacturing or repairing thereof characterised by the materials used therefor
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/18—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mixtures of the silica-lime type
  • C04B28/186—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mixtures of the silica-lime type containing formed Ca-silicates before the final hardening step
  • C04B28/188—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mixtures of the silica-lime type containing formed Ca-silicates before the final hardening step the Ca-silicates being present in the starting mixture
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
  • C04B35/22—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in calcium oxide, e.g. wollastonite
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/71—Ceramic products containing macroscopic reinforcing agents
  • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
  • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00939—Uses not provided for elsewhere in C04B2111/00 for the fabrication of moulds or cores
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
  • C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3427—Silicates other than clay, e.g. water glass
  • C04B2235/3436—Alkaline earth metal silicates, e.g. barium silicate
  • C04B2235/3454—Calcium silicates, e.g. wollastonite
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5212—Organic
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5216—Inorganic
  • C04B2235/522—Oxidic
  • C04B2235/5232—Silica or silicates other than aluminosilicates, e.g. quartz
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5216—Inorganic
  • C04B2235/524—Non-oxidic, e.g. borides, carbides, silicides or nitrides
  • C04B2235/5248—Carbon, e.g. graphite
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/526—Fibers characterised by the length of the fibers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5264—Fibers characterised by the diameter of the fibers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
  • C04B2235/9669—Resistance against chemicals, e.g. against molten glass or molten salts
  • C04B2235/9676—Resistance against chemicals, e.g. against molten glass or molten salts against molten metals such as steel or aluminium
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• This invention relates to a novel material for use in casting low melting point non-ferrous metals.
• the casting of molten non-ferrous metals such as aluminium, tin, zinc etc. involves the direct contact of the molten metal with the parts of the casting equipment such as pouring boxes, launders and troughs, furnace linings, supply channels, spouts, and hot top rings, and it is important that such equipment be produced from, or at least lined or faced with, a material having suitable properties. Amongst these are that the material should have good thermal insulating properties, low heat capacity, high fracture toughness, low oil absorption potential, and should not be wet by the molten metal.
• xonotlite is of particular benefit, due to its low water content and low shrinkage.
• xonotlite is difficult to make, requiring for example extremely rigorous steam curing, high pressure tolerance vessels and high energy costs, and also expensive raw materials such as SiO 2 of very high purity.
• Tobermorite is an alternative calcium silicate matrix for making metal casting equipment, being easier and cheaper to make, but it suffers from exhibiting more water of crystallisation than xonotlite and a higher shrinkage.
• the shrinkage problem can be overcome by including in the composition 10-20 wt% of fibrous wollastonite and 20-30 wt% of crystalline alumina, the alumina serving to dilute the tobermorite and reduce the shrinkage and water evolution, and also to improve the effectiveness of the carbon reinforcing fibres.
• the raw material for the production of the material contains a proportion of pre-autoclaved calcium silicate.
• a process for producing a material for the manufacture of metal casting equipment comprising forming an aqueous slurry comprising (a) ingredients for the formation of a calcium silicate matrix and (b) polyacrylonitrile-based carbon fibre; mixing said slurry to form a viscous paste; extruding said viscous paste into the desired form; and autoclaving said form at such a temperature and pressure, and for such a time, as is necessary to convert the ingredients (a) into a calcium silicate matrix substantially comprising tobermorite, wherein the aqueous slurry contains from 1.5 to 25%, by weight based on the slurry solids content, of a pre-autoclaved calcium silicate slurry.
• the invention is based upon the surprising discovery that the fineness and rheology of the pre-autoclaved calcium silicate assists in the wetting and dispersion of the carbon fibres and substantially improves their effectiveness in reinforcing the material and preventing crack propagation.
• the matrix substantially comprising tobermorite is intended to mean that the calcium silicate matrix comprises at least 50%, by weight, of tobermorite; preferably the matrix comprises more than 80%, most preferably more than 85%, by weight, of tobermorite.
• the matrix may also contain minor amounts of other forms of calcium silicate, especially xonotlite.
• the calcium silicate body is reinforced with polyacrylonitrile-based carbon fibres.
• the carbon fibres are suitably present in the body in an amount between 0.2 and 12%, by weight, preferably 0.5 to 5% by weight. They may suitably have a length between 1 and 15 mms, preferably 2 to 5 mms, and a fibre diameter of 4 to 20 microns, preferably 7 to 10 microns.
• the moulded body may also comprise other inert fillers dispersed throughout the matrix. These may constitute from 20 to 75%, by weight, of the moulded body, and a particularly useful inert filler is wollastonite in fibrous form. Wollastonite is especially suitable in an amount of 45 to 55%, by weight, based on the weight of the body.
• the aqueous slurry may also contain any desired inert filler, for example fibrous wollastonite, and it has also been found that it is of advantage to include in the slurry, in an amount of between 0.1 and 3% by weight of the solids content of the slurry, organic fibres of length 1 to 8 mms, to assist in the moulding of the slurry.
• organic fibres may be natural or synthetic organic fibres, e.g. bleached or unbleached wood fibre or other modified cellulose fibres.
• aqueous slurry of a small amount, i.e. 1.5 to 25% by weight on the slurry solids content, of a pre-autoclaved calcium silicate slurry.
• This can be of either tobermorite or xonotlite, and helps to disperse the carbon fibres uniformly throughout the aqueous slurry, with the advantageous results mentioned above. It is suitably made by autoclaving an aqueous slurry of calcium hydroxide and siliceous material in a CaO/SiO 2 mole ratio of 0.6 to 1.2, in a stirred pressure autoclave at a pressure of 7 to 30 bar for about 1 to 10 hours.
• the materials used for the production of the calcium silicate slurries used herein may be, as the calcareous component, lime (calcium hydroxide), calcium oxide or Ordinary Portland Cement; and, as the siliceous component, high purity quartz silica flour, amorphous silica, silica fume or diatomite, for example.
• Example 1 Pre autoclaved calcium silicate slurry 1.5 20.0 2.0 2. Natural cellulose fibre 0.5 2.0 3.0 3. Fibrous wollastonite 20.0 35.0 60.0 4. Carbon fibre, 3mm (P.A.N. - based) 2.0 2.0 3.0 5. Ca(OH) 2 38.5 20.8 8.6 6. SiO 2 37.5 20.2 8.4 7. Calcium silicate fines - - 15.0 Lime and silica are mixed in water and autoclaved at a temperature of about 200°C and a pressure of about 18 bar for about 3 hours to produce a slurry (1).
• the lime (5) and silica (6) are then mixed in water.
• the wollastonite (3) is then added, together with any calcium silicate fines (7), and thoroughly mixed in, followed by the cellulose fibres, which are also thoroughly mixed.
• the slurry (1) is then added, followed by the carbon fibres (4), and the whole is mixed to form an aqueous slurry. This is then formed into shape and water removed. Typically the slurry may be extruded into pipe form or, more likely, sheeted out in sheet or board form. A pressure of 10-30 bar will remove substantially all the water.
• the moulding is then subjected to autoclaving at 7-14 bar, typically 10 bar, for about 12 hours to produce a calcium silicate matrix of substantially tobermorite reinforced with carbon fibres and containing wollastonite and natural cellulose fibres.
• autoclaving at 7-14 bar, typically 10 bar, for about 12 hours to produce a calcium silicate matrix of substantially tobermorite reinforced with carbon fibres and containing wollastonite and natural cellulose fibres.
• the moulding is dried, sanded and/or trimmed to final shape and heat-treated in air or in a chemically inert gas, for example nitrogen or carbon dioxide, at about 300°C to 850°C for 12 hours to remove any remaining water.
• a chemically inert gas for example nitrogen or carbon dioxide
• the final products will typically have compositions as follows, on a dry weight basis:- % by weight
• Example 1 Example 2
• Example 3 Wollastonite 20.1 35.7 61.86 Carbon fibres 2.01 2.04 3.09 Xonotlite 1.51 20.4 2.06 Tobermorite 76.38 41.83 17.52 Calcium silicate fines - - 15.46 % Tobermorite in Matrix 98.1 67.2 89.5
• the dry densities of the finished products will normally be in the range 500-1500 kg/m 3 .
• the materials are extremely durable when in contact with molten aluminium and other non-ferrous metals, and have a high toughness and strength. They are resistant to thermal cracking when in contact with molten metal. Their thermal shrinkage (less than 0.2% at 750°C) compares well with material produced according to GB-A-2 173 505 (greater than 0.3%), and their flexural strength, at 17mPa, compares well with that (9mPa) of material according to GB-A-2 173 505.
• the low oil absorption is a particular feature of the materials of the invention. This feature is very important in, for example, the casting of aluminium where oil is used in contact with calcium silicate parts. Absorption of oil causes softening and degradation of the physical properties of the calcium silicate and early failure of the parts. In addition, at the high temperatures involved the absorbed oil decomposes and the gases so produced cause defects on the surface of the cast metal.
• Example A The procedure was the same as for Example A but in this case the samples were first immersed in molten aluminium at 700°C for 30 minutes. The results are shown in Table 2.
• the material made in accordance with the invention is predominantly useful in the manufacture of metal casting equipment. However, because of its excellent physical and thermal properties it is proposed that it will replace asbestos-reinforced calcium silicate in many applications.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

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• 1995
  • 1995-09-14 GB GBGB9518787.8A patent/GB9518787D0/en active Pending
• 1996
  • 1996-09-13 DE DE69621537T patent/DE69621537T2/de not_active Expired - Lifetime
  • 1996-09-13 EP EP96306645A patent/EP0763392B1/de not_active Expired - Lifetime

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